This invention relates to a powered system, such as a train, an off-highway vehicle, a transport vehicle, and an agriculture vehicle, and more particularly to braking systems in such vehicles or other powered systems. Some powered systems (such as, but not limited to, off-highway vehicles, transport vehicles such as transport buses, agricultural vehicles, and trains or other rail vehicle systems) are powered by one or more diesel power units, or diesel-fueled power generating units. With respect to rail vehicle systems, the diesel power unit is typically a diesel internal combustion engine that is a part of a locomotive, with the locomotive(s) being part of a train that further includes a plurality of rail cars, such as freight cars. Usually more than one locomotive is provided, wherein a group of locomotives within a train is commonly referred to as a locomotive “consist.” A train may have one or more locomotive consists, or groups of locomotives, separated by one or more train cars, based upon the particular configuration of the train. Locomotives are complex systems with numerous subsystems, with each subsystem being interdependent on other subsystems.
Powered systems, such as a locomotive consist, for example, include various types of braking systems, such as a dynamic braking system, for example. A controller may operate in an automatic mode, in which a motoring output (i.e., motoring power) of an engine is predetermined at incremental locations along a route when the locomotive consist operates in a motoring mode, and in which a braking output (i.e., braking power) of the engine is predetermined at incremental locations along the route when the locomotive consist operates in a braking mode.
Various regulations, including FRA (Federal Railroad Administration) regulations, impose maximum limits on the braking effort of a locomotive consist during a trip along a route. Among other reasons, such regulations are imposed to reduce instances of train derailment due to over braking. A distinct FRA regulation may be imposed for each locomotive consist within a single train, based on one or more characteristics of the particular locomotive consist. Conventional techniques have been proposed to ensure that the braking effort of the locomotive consist does not exceed the FRA regulation. Such a conventional technique involves disconnecting a braking system and/or one or more axles from the braking system of one or more of the locomotives within the locomotive consist prior to the commencement of a trip along the route, such that the maximum braking effort of the remaining connected braking systems within the locomotive consist cannot exceed the FRA regulation. However, the disconnected braking system cannot be reconnected during routine operation of the locomotive consist, and thus such a conventional technique limits a maximum braking effort of the locomotive consist, particularly at high speeds, as the braking effort is inversely proportional to the speed of the locomotive consist. Additionally, if a conventional locomotive consist includes one locomotive having a connected braking system and another locomotive having a disconnected braking system, and the connected braking system suddenly fails to operate, the disconnected braking system on the other locomotive cannot be utilized to provide the lost braking effort. Additionally, if the braking system of the one or more locomotives is not disconnected, the collective braking effort of the locomotive consist may exceed the FRA regulation, particularly at low speeds. Accordingly, substantial drawbacks are encountered irrespective of whether a braking system of the one or more locomotives is disconnected or not disconnected. Additionally, if one or more axles are disconnected from the powered system of the locomotive, this may cause one of several changes to the braking effort of the locomotive, such as reducing the braking effort by the fraction of the disconnected axles (e.g., ⅙), reducing the maximum braking power of the engine, and/or eliminating all of the braking effort of the locomotive, for example, which complicates the determination of how many axles can be disconnected.
Heretofore, the ability to control the braking effort of a locomotive consist such that the braking effort does not exceed a braking effort limit (e.g., as established by an FRA regulation) has not been ascertainable without substantially limiting a maximum available braking effort, thereby sacrificing braking efficiency. Thus, it would be advantageous to provide a system which controls the braking effort of the locomotive consist such that it does not exceed the braking effort limit, while maximizing the braking effort of the locomotive consist, to improve an overall braking efficiency of the locomotive consist.